The following apparatus and procedures were elaborated: 1) An apparatus for the measurement of segmental voltages across electrofocusing gels; 2) An apparatus for the simultaneous PAGE analysis in different buffers or detergents; 3) A continuous rate decelerator for elution pumps used in preparative PAGE; 4) An electrophoretic protein concentration device; 5) A procedure for the bridging of conductance gaps in electrofocusing at high ionic strength; (6) An apparatus for the automated measurement of 14C-labeled zones on polyacrylamide gels.